Cover for insulator assembly

ABSTRACT

An improved cover for protecting insulators used with high voltage transmission lines from contamination. The cover is generally bell shaped and has a lower end fitted over the insulator assembly; when in position, the cover is coaxial with the insulator assembly, and the coaxial relationship is maintained by means of ribs formed on the inner wall of the cover which engage the outer edge of the insulator assembly. The lower end of the cover is dimensioned so that there is adequate clearance between the cover and the lower portion of the insulator assembly, to prevent current for arcing over to the outer surface of the cover.

United States Patent Ellaschuk [151 3,692,927 [451 Sept. 19, 1972 1 COVER FOR INSULATOR ASSEMBLY [22] Filed: June 1, 1971 [21] Appl.No.: 148,415

[30] Foreign Application Priority Data Lehman 174/5 R X 3,327,280 6/1967 Levine et a1. ..174/ 138 F X FOREIGN PATENTS OR APPLICATIONS 705,117 4/1966 Italy "174/139 385,699 l/ 1933 Great Britain ..174/5 R Primary Examiner-Laramie E. Askin Attorney- -Rogers, Bereskin & Parr [57] ABSTRACT An improved cover for protecting insulators used with high voltage transmission lines from contamination. The cover is generally bell shaped and has a lower end fitted over the insulator assembly; when in position, the cover is coaxial with the insulator assembly, and the coaxial relationship is maintained by means of ribs formed on the inner wall of the cover which engage the outer edge of the insulator assembly. The lower end of the cover is dimensioned so that there is adequate clearance between the cover and the lower portion of the insulator assembly, to prevent current for arcing over to the outer surface of the cover.

2 Claims, 4 Drawing Figures PATENTEDSEP 19 1912 INVENTIOR EDWIN IVAN ELLASCHUK COVER FOR INSULATOR ASSEMBLY This invention relates to a shield or cover for insulator assemblies used with high voltage transmission lines.

High voltage transmission lines are commonly supported by insulator assemblies that are suspended from large metal towers. If the insulator assemblies become coated with conductive dust,- current may arc across the insulator and burn the portion of the tower from which the insulator assembly is suspended. This problem is particularly severe, for example, in areas near potash mines because potash dust is a highly conductive salt.

The present invention protects the insulator as sembly from contamination in the following manner. A generally bell shaped cover having an open lower end is fitted over the insulator assembly; when in position, the

cover is coaxial with the insulator assembly. The lower end of the cover is dimensioned so that there is adequate clearance between the cover and the lower portion of the insulator assembly, to thereby prevent current from arcing over to the outer surface of the cover.

In drawings illustrating a preferred embodiment of the invention,

FIG. 1 is a side elevational view showing a cover positioned over an insulator assembly,

FIG. 2 is a perspective view taken from the underside of the cover shown in FIG. 1.

FIG. 3 is a side elevational view of another embodiment of the invention, and

FIG. 4 is a perspective view of the cover shown in FIG. 3.

Referring to the drawings, a cover for use with a high voltage insulator assembly is generally indicated by reference numeral 10. A typical insulator assembly is shown in FIG. 1, and it consists of a plurality of spacedapart ceramic discs 11 that are coupled together along a common axis. The upper end of the insulator assembly is provided with a hook eye 12, to facilitate attachment of the insulator assembly to a tower crossarm (not shown). The lower end of the insulator assembly has a clamp 13 to which a high voltage line 14 may be attached.

The cover consists of a generally bell-shaped housing or shell 15 that flares outwardly slightly from its upper wall 16 to its bottom edge 17. The shell 15 is generally circular in cross-section, and its lower end is open, as shown in FIG. 2. The bottom edge 17 of the shell 15 is sufficiently spaced from the lowermost insulator disc 11 so that current cannot arc across the gap between the lowermost insulator disc 11 and the outer surface of the shell 15. The shell 15 is constructed of a rigid insulating material, such as resin impregnated glass fiber.

The upper wall 16 of the shell 15 is provided with a central opening 18 which is just of sufiicient size to permit the upper end of the insulator assembly (including the hook eye 12) to pass therethrough; the edges of the opening 18 can be covered with any suitable sealant to prevent dust from entering any space between the insulator assembly and the edge of the opening 18.

The insulator assembly may sway somewhat from side to side due to wind. It is important that the cover 10 maintain its coaxial relationship with the insulator assembly during such movement, to prevent the lower edge of the cover from touching the lowermost insulator discs 11. This may be accomplished by forming a plurality of channel-shaped ribs 19 on the inside of the shell 15. In FIG. 2 four of such ribs are shown, and they are equi-angularly spaced. The length of the ribs 19 is such that they overlap the three uppermost insulator discs 11, as shown in FIG. 1, and the radial dimension of the ribs 19 is such that their inner ends snugly engage the said insulator discs 1 l.

The cover 10 can be modified to suit other forms of insulator assemblies. For example, the insulator as sembly used with transmission lines of extremely high voltage may be longer than the one shown in FIG. I, and may utilize a larger number of insulator discs 11. In such a case, the ribs 19 could be extended in length to cover more of the insulator discs 11 and thereby give the cover increased stability; similarly, the diameter of the lower edge 17 of the cover 10 could be increased to suit the higher voltage.

Finally, it is important that the lower edge 17 of the cover 10 be quite rigid. In some cases it may be desirable to reinforce the lower end 17 of the cover 10 with an additional band of resin impregnated glass fiber.

The embodiment shown in FIGS. 3 and 4 is designed to be used with insulator assemblies of the so-called pin type, as indicated by reference numeral 20 in FIG. 3. The insulator assembly 20 has a ceramic upper portion 21 and a metallic downwardly extending pin 22 which can be attached to any suitable support. A high voltage transmission line 23 may be secured to the upper end of the insulator assembly 20 by any conventional means. In this case the cover for the insulator assembly consists of a shell 24 having a pair of diametrically opposite slots 25 which are just wide enough to pass the transmission line 23. The slots 25 extend from the bottom of the shell 24 to near the upper end thereof. In order to prevent contamination from reaching the insulator assembly after the shell 24 is in place, a pair of pivotable cover plates 26 are provided, and it will be noted that the upper ends thereof are provided with a cut-out portion to accommodate the line 23 when the cover plates 26 are positioned to close the slots 25. As in the case of the shell 15 shown in FIG. 1, the shell 24 is provided on its inside surface with four equi-angularly spaced ribs 27 which engage the outer surface of the insulator assembly 20 and maintain the shell 24 and the insulator assembly 20 in coaxial relationship. In this case, the ribs 27 are arranged on the inner wall of the shell 24 so that they do not interfere with the line 23, i.e. the slots 25 are formed in the shell 24 mid-way between two adjacent ribs 27. The shell 24 may be constructed of the same material as the shell 15.

What I claim is:

1. A cover for protecting a high voltage insulator assembly from contamination, comprising: a shell having a side wall and a top wall and an open lower end, said shell being shaped to substantially enclose said insulator assembly and being adapted to be supported in coaxial relation with said insulator assembly, said shell being composed of a rigid, substantially non-conductive material and being dimensioned so that the clearance between said shell and said insulator assembly at the lower end thereof is sufficient to prevent arc over, means within said shell for engaging at least a shell adjacent said slots, said cover plates having cutout portions in the respective upper edges thereof to accommodate said line when said cover plates are positioned to close said slots.

2. A cover as claimed in claim 1 wherein said means within said shell comprises a plurality of equi-angularly spaced ribs formed on the inside wall of said shell.

* I I I I 

1. A cover for protecting a high voltage insulator assembly from contamination, comprising: a shell having a side wall and a top wall and an open lower end, said shell being shaped to substantially enclose said insulator assembly and being adapted to be supported in coaxial relation with said insulator assembly, said shell being composed of a rigid, substantially nonconductive material and being dimensioned so that the clearance between said shell and said insulator assembly at the lower end thereof is sufficient to prevent arc over, means within said shell for engaging at least a portion of the outer edge of said insulator assembly to thereby maintain said shell coaxial with said insulator assembly, said shell having two diameTrically opposite slots respectively extending from the bottom of the shell to points near the top of the shell to permit the shell to be slipped over an insulator assembly having a high voltage line attached to the upper end thereof, and two cover plates respectively pivotally attached to said shell adjacent said slots, said cover plates having cut-out portions in the respective upper edges thereof to accommodate said line when said cover plates are positioned to close said slots.
 2. A cover as claimed in claim 1 wherein said means within said shell comprises a plurality of equi-angularly spaced ribs formed on the inside wall of said shell. 